Electric lamp with tubular body and light transmitting closure having over-lapping flange seal



3,3ZLQQ2 TTING May 23, 1967 J. J. PALERMO ETAL ELECTRIC LAMP WITH TUBULAR BODY AND LIGHT TRANSMI CLOSURE HAVING OVER*LAPPING FLANGE SEAL 2 Sheets-Sheet 1 Filed July 2, 1962 FIG? J jig) FIGZ F I G. 5

JAMES .1. PALERMO ROBERT P. BONAZOLI ROBERT F? SCOLEDGE EMERY G. AUDESSE ATTORNEY y 23, 1957 .1. J. PALERMO ETAL. 3,321,662

ELECTRIC LAMP WITH TUBULAR BODY AND LIGHT TRANSMITTING CLOSURE HAVING OVER-LAPPING FLANGE SEAL 2 Sheets-Sheet 2 Filed July 2, 1962 20 JAMES J. PALERMO m ROBERT F. BONAZOLI ROBERT F SCOLEDGE I I EMERY a AUDESSE INVENTORS United States Patent ELECTRIC LAMP WITH TUBULAR BODY AND LIGHT TRANSMITTING CLOSURE HAVING OVER-LAPPING FLANGE SEAL James J. Palermo, Salem, N.H., and Robert P. Bonazoli, Hamilton, Robert F. Scoledge, Danvers, and Emery G. Audesse, Salem, Mass., assignors to Sylvania Electric Products Inc., a corporation of Delaware Filed July 2, 1962, Ser. No. 206,881 4 Claims. (Cl. 313-315) This invention relates to incandescent lamps and particularly to incandescent lamps having a high power output in a small envelope, and to methods of making such lamps.

The invention is particularly useful in the so-called iodine incandescent lamp, in which a small amount of iodine vapor is present in the envelope to prevent blackening of the latter during the useful life of the lamp, in acordance with the well-known tungsten-iodine cycle. Such iodine lamps are generally in the form of enlongated sealed tubes, with a coiled filament along the axis of the tube, each end of the tube having a flat pressed seal through which a lead-in conductor extends from the filament. Such tubular lamps, however, are difficult to make in extremely small sizes, and have the disadvantage of requiring electrical contact means at each end.

We have discovered that a very compact iodine lamp can be made by supporting a coiled filament between two lead-in wires which pass through a single pressed seal, at one end of a very small sealed bulb whose oposite end is in the form of a thin flat glas disc, hermetically sealed thereto. The disc can be a glass lens, if desired. The resultant device will be capable of withstanding very high shock forces, thereby extending the field of application of the lamp. The word glass is used in a broad sense, including quartz and other highly refractory glasses.

The external contacts, being entirely at the back of the lamp, do not interfere with the light emitted forwardly.

The usual tubular iodine lamp has an exhaust tube midway between its ends. In the present lamp, that would correspond to an exhaust tube at the forward or flat disc end of the bulb, which would destroy the effectiveness of the light emission through that end, and would prevent the use of a lens as the disc. This is especially true where the lamp is small, and the exhaust tube would occupy a considerable proportion of the light-emitting area. The exhaust tube cannot extend from the press seal at the contact end of the bulb, because of the small space available and the shape of the press seal.

We have discovered, however, that the device can be made without any exhaust tube at all on the finished lamp, and have discovered a method of so making the lamp.

Our method includes sealing the lamp mount into one end of an elongated glass tube, the glass tube being sealed at its other end and having an exhaust tube intermediate the two ends and preferably in the middle of the tube. Before sealing the glass tube, a small loosely-fitting glass disc or lens is slipped into the tube, and a shoulder is provided on the inside surface of the glass tube above the filament, so that the glass disc can be brought to rest against the shoulder. The entire tube can then be exhausted throughthe exhaust tube and filled to the proper pressure with a suitable filling gas such as argon or nitrogen and a small amount of iodine.

After the tube is evacuated and filled with the desired gases, small pin-point flames are applied to the outside of the tube in register with the outer circumference of the glass disc until the glass is heated sufiiciently so that an hermetic seal wil be effected between the tube and disc. Once the seal is completed, the glass tube is cut oif from the end of the lamp above the disc, and the edges firepolished if desired.

The result will be a lamp having no exhaust tube and whose forward or light-emitting portion is a fiat glass disc from which a small bulb-like tube extends rearwardly to merge into a press seal through which two or more lead-in conductors extend for contacts to an external circuit.

In some cases it may be desirable to have a filament at each end of the tube and two discs in the tube so that a small lamp can be made and cut off from each end of the tube thereby increasing the efficiency of the manufacture.

The glass disc inside the lamp can be replaced by a cupshaped glass member, that is a short hollow cylinder closed at one end, with the open end of the cup facing the nearest end of the lamp. In that case the shoulder inside the tube can be omitted, and the open rim of the cup allowed to rest on the sealed end of the lamp, with the closed end of the cup enough away from the sealed end of the lamp so as not to touch the filament. By this method, the sealing of a small-diameter tube inside a larger-diameter tube is unnecessary, and a single-diameter tube can be used. The cylindrical sides of the cup have an outside diameter slightly less than the inside diameter of the main portion of the tube, and after evacnation and gas-filling of the device are sealed to the outer lamp tube.

Other objects, advantages and features of the invention will be apparent from the following specification taken in connection with the accompanying drawing in which:

FIGURE 1 is a view of two tubes of different diameters which are to be sealed together;

FIGURE 2 is a view of the two tubes sealed together at their adjacent ends, one tube being slightly inside the other;

FIGURE 3 shows the tube of smaller diameter shortened and an exhaust tube sealed to the tube of larger diameter.

FIGURE 4 shows the same device with the smaller tube pressed to form a seal, through which lead-in wires extend to support a filament, the view also showing a small glass disc loosely fitting inside the tube;

FIGURE 5 shows a tube sealed at both ends with the filament in place at one end for sealing the disc to the tube;

FIGURE 6 shows the finished lamp after being cut from the tube of which it was originally a part;

FIGURE 7 shows a cross-section of the same lamp through a middle plane transverse to that of FIGURE 6; and

FIGURE 8 shows a top view of the lamp.

FIGURE 9 is a view of a lamp ready for processing, using a glass cup instead of a disc.

In making a lamp according to the invention a hollow glass tube 1 and another glass tube 2, whose outer diameter is slightly smaller than the inside diameter of tube 1, are lined up with each other. As shown in FIGURE 2, the tube of smaller diameter 2 is pushed a short distance into an adjacent end of tube 1 and the two tubes then sealed together, the smaller tube forming the shoulder 3 inside the end of the larger tube 1. Up to this point the tube 2 has been kept rather long for convenience in handling and the excess is now out off leaving only a small length of tube 2 extending from FIGURE 1. An exhaust tube 4 is sealed into the side of the tube 1 and considerably away from the shoulder 3.

The open end 5 of the smaller tube 2 is now pressed together to form a fiat press through which the molybdenum ribbons 6, 7 are sealed, one end of each ribbon being joined to a lead-in wire 8, 9 which extends out of the glass seal at its external end. The other end of each ribbon 6, 7, is joined to a support wire 10, 11 which extends therefrom into the tube to carry a coiled filament 12. The filament is generally a coiled-coil as shown a more clearly in FIGURE 6, and the primary or smaller coil of the coiled-coil may extend straight downwardly over the support wires and 11 and be fixed thereto. A thin glass disc or lens 13 is slipped onto the open end into the tube 1. This disc should have a diameter somewhat smaller than the inside diameter of tube 1, so that it may slip easily down the tube, as shown by the arrow in FIGURE 4, when the tube is placed vertically as in FIGURE 5. For example, if tube 1 is of 0.300 inch inside diameter, the disc 13 can be of 0.284 inch outside diameter, or may even have a diameter somewhat close to the inside diameter of the outer tube 1. The end 14 of tube 1 is sealed off, for example to form a press seal 15, as shown in FIGURE 5, at the top of the tube, or in some other convenient manner. The device is exhausted and filled in the usual way with a suitable filling gas such as nitrogen or argon and a small amount of iodine. The disc being loose-fitting, will permit evacuation and filling of the portion 16 of the tube below the disc, when in the position shown in FIG. 5. However, the evacuation and gas-filling will be greatly facilitated if the disc 13 is in the position shown in FIG. 4, or is in a position with its flat sides parallel to the longitudinal axis of tube 1 instead of transverse to it, during the exhausting and filling. Flames of a narrowed, pin point type to confine their heat to a small portion of the glass are applied to opposite sides of the glass tube 1 and in horizontal relationship with the disc 13 and the glass suificiently to elfect a permanent hermetic seal between the disc 13 and the tube 1, the disc 13 resting on the shoulder 3.

After the disc 13 is sealed to the tube 1, as in FIG. 6, the tube 1 is cut off flush with the top of the disc, and the remaining cut edges ground or fire-polished, is desired, resulting in the finished lamp of FIGS. 6, 7 and 8.

In these figures, the disc 13 is the top portion of the lamp as shown in FIG. 6 and all that remains of outer tube 1 is the outer portion of the cylindrical wall of the lamp as shown. The inner portion of the wall is what was once the smaller-diameter tube 2, and is so marked in the figures. The filament 12 can be of a coiled coil type, and if the tubes 1 and 2 were of about 0.375 inch and 0.300 inch outside diameter respectively, and each about 0.035 inch thick, with the disc 13 having about the same thickness, and the formed bulb of the lamp being about fitinch from the beginning of the press seal to the top of the disc 13, this distance being denoted by A in FIG. 7. In such a small lamp, made of quartz, a power input of 100 watts was used, the filament being a coiled-coil tungsten filament designed for that wattage. The diflerence in size between this kind of 100-watt lamp and the usual 100-wat-t lamp sold for home use, and generally having a bulb about 2 /8 inches in diameter, is quite apparent. Moreover, the construction of our resultant bulb is much more resistant to shock than is the usual incandescent bulb.

A modified method of making a lamp is illustrated in FIG. 9. In this, the tube 1 is sealed ofi directly at one end by a press seal carrying the filament 12, rather than through the intermediary of a smaller diameter tube 2. The shoulder which the latter tube would provide is not used in FIG. 9, because the disc 13 is now in the form of a cup 20, that is of a hollow cylinder 21 with the disc 13 sealed to and closing one end. At its open end the cylinder 21 will rest on the press seal, thereby spacing the disc 13 above the filament. The cup is placed in the tube 1 while the end 22 of the bulb is open, before sealing it as at seal 23.

The cup 20 makes a slightly loose fit in the tube 1 to permit evacuation and gas-filling of the end of the tube around the filament 12. After the evacuation and gasfilling, the cylinder 21 is sealed to the tube 1, and then the latter cut off flush with the side of the disc 13 flush with the filament, as before.

Although a particular lamp has been described, the examples are given merely as illustrative, and various modifications can be made by a person skilled in the art without departing from the spirit and scope of the invention. For example, a reflecting coating of metal or of the so-called dichroic types, can be used on the outside of the bulb portion 25, or even on the inside, if very refractory materials are used. Platinum and palladium would be good metal coatings for high temperatures; dichroic materials are shown in a copending application Ser. No. 24,101, filed Apr. 21, 1960 by R. F. Scoledge et al.

The word light as used in the appended claims includes all forms of radiation emitted from an incandescent filament or electric discharge, such as infra-red and ultraviolet in addition to visible light, and a light-transmitting piece is intended to mean a piece transmitting any desired light in any or all of the ultraviolet visible and infra-red regions.

Although the invention has been described with respect to an incandescent lamp, it can also be used in an electric discharge lamp, in which the lead-in wires would carry electrodes through which a discharge could be passed.

What we claim is:

1. An electric lamp comprising a glass body formed of a hollow tubular portion having a pressed sealed portion closing one end of said tubular portion, a light-transmitting piece closing the other end of said other tubular portion and an integral tubular flange projecting from the periphery of said light-transmitting piece, said flange fitting into engagement with the surface of the hollow tubular portion in a peripheral overlapping marginal area thereof around the end of said tubular portion, said light-transmitting piece, integral flange and marginal area being fused together forming a permanent hermetic seal of said other end of the hollow tubular portion, a pair of ribbon lead-in conductors sealed through said pressed seal, and a coiled-coil wire filament attached to the inner end of said conductors.

2. The combination of claim 1, in which the axis of the coiled-coil is disposed in parallelism to the surface of the light-transmitting piece.

3. The combination of claim 1, in which the Wire filament is tungsten and a filling of iodine vapor at low pressure is sealed in said envelope.

4. The combination of claim 1 in which the contour of the lamp is unbroken by an exhaust tube.

References Cited by the Examiner UNITED STATES PATENTS 1,433,982 10/1922 Cameron 313-- 2,464,990 3/1949 Plagge 313113.1 2,473,900 5/ 1949 Perron 31620 2,491,237 12/1949 Way 313-333 2,802,130 8/1957 Engelman 313-110 2,883,571 4/1959 Fridrich et al. 313--323 2,904,716 9/1959 Malm et al. 313-318- 2,914,371 11/ 1959 Wiedermann 31620 3,027,481 3/1962 Baber 313-110 3,094,642 6/1963 Duval 313--222 JAMES D. KALLAM, Primary Examiner. 

1. AN ELECTRIC LAMP COMPRISING A GLASS BODY FORMED OF A HOLLOW TUBULAR PORTION HAVING A PRESSED SEALED PORTION CLOSING ONE END OF SAID TUBULAR PORTION, A LIGHT-TRANSMITTING PIECE CLOSING THE OTHER END OF SAID OTHER TUBULAR PORTION AND AN INTEGRAL TUBULAR FLANGE PROJECTING FROM THE PERIPHERY OF SAID LIGHT-TRANSMITTING PIECE, SAID FLANGE FITTING INTO ENGAGEMENT WITH THE SURFACE OF THE HOLLOW TUBULAR PORTION IN A PERIPHERAL OVERLAPPING MARGINAL AREA THEREOF AROUND THE END OF SAID TUBULAR PORTION, SAID LIGHT-TRANSMITTING PIECE, INTEGRAL FLANGE AND MARGINAL AREA BEING FUSED TOGETHER FORMING A PERMANENT HERMETIC SEAL OF SAID OTHER END OF THE HOLLOW TUBULAR PORTION, A PAIR OF RIBBON LEAD-IN CONDUCTORS SEALED THROUGH SAID PRESSED SEAL, AND A COILED-COIL WIRE FILAMENT ATTACHED TO THE INNER END OF SAID CONDUCTORS. 